<!DOCTYPE html>
<html>
  <style>
    :-moz-read-only { color: green; }
    :-moz-read-write { color: red; }
  </style>
  <body onload="document.designMode='on';document.designMode='off'">
    <div>test</div>
    <div contenteditable></div>
  </body>
</html>
